1. Field of the Invention
The invention relates generally to hydratable apparatus for mounting emergency or caution light bars on the cab of a truck, and more particularly, to a light bar support which may be raised or lowered to adjust the vertical profile of the vehicle on which it is mounted.
2. History of the Prior Art
Tow trucks and construction pickup trucks used highways, as well as police pickup trucks used for pursuit work, must be equipped with an overhead flashing light bar so that they can be seen by approaching traffic when they are being driven slowly, parked on the shoulder of a highway or street, or (in the case of police vehicles) being used in a pursuit mode. One of the problems associated with having a light bar installed on a level where it can be seen from all directions is that vertical clearances, particularly in parking garages, may be severely limited. In other words, a truck equipped with a non-retractable light bar may not be able to enter the parking garage. Although low profile light bars having a high of only about two inches (roughly 51 mm) are now available, that height may be just enough of an addition on a high-profile vehicle, to make the vehicle unable to enter low parking garages that are designed primarily for conventional automobiles and normal-height pickup trucks and vans.
While a variety of devices has been developed for the elevation of individual light fixtures above the roof level of a motor vehicle, they are generally inadequate for use with modern light bars. Some of these known devices use telescoping tubes to support a single light fixture at varying heights. Such telescoping arrangements are neither strong enough to support a light bar nor permissive of the minimal elevations desired in the lower nonemergency or transport position. Other such devices use end pivot arrangements which are not of sufficient strength to dependably support a modern light bar and furthermore generally rotate the light fixture from a horizontal to a vertical condition as the pivoting arm of the device rotates from horizontal to vertical.
U.S. Pat. No. 5,558,424 to Stephen J. Zeligson discloses an emergency vehicle light bar mounting assembly that employs first and second connected and substantially horizontal elongated frames mounted transversely across the upper surface of an emergency vehicle. The connecting assembly is such that the second frame may be substantially continuously vertically displaced while maintaining parallel relationship of the frames so that the emergency indicating equipment fixed atop the second frame maintains its operational attitude regardless of the elevation to which the second frame is raised. Reciprocable operation of the connecting assembly is accomplished with an electric, hydraulic, pneumatic or manual drive system. Although this mounting assembly has the capability of raising and lowering a light bar, it still may not provide a sufficiently low profile for a vehicle to enter a parking garage having a particularly low vertical clearance. This is especially true if the mounting assembly and light bar are installed on a heavy-duty truck, which already has a relatively high vertical profile.
What is needed, therefore, is an emergency light bar mounting assembly that will allow the light bar to be retracted to a level that will provide maximum vertical clearance so that the vehicle may have expanded access to covered facilities having minimal vertical clearances.